The first calixarenequinhydrone: syntheses, self-organized films and solvatochromism

J Incl Phenom Macrocycl Chem

et al. 2011

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The electrochemical reduction of di(methoxyp-tert-butyl)calix [4]arenediquinone led to its calix[4]arenedihydroquinone. The presence of both in the solution refers to the generation of calix[4]arenequinhydrone charge-transfer complex at the electrode surface through a donor/acceptor process type. Self-assembled adlayers of calix[4]arenequinhydrone was obtained by partial electrochemical reduction. Electrochemical deposition of the last form was achieved on the platinum disk electrode at -1.16 V versus SCE (saturated calomel electrode) in aprotic solution by cathodic reduction of the starting substrate. The deposit was first characterized by cyclic voltammetry (CV) in electrolytic solution and then in electrolyte support solution and finally in a ferricyannure solution. The self-assembled product was characterized by MALDI-TOF Mass and IR spectroscopy techniques. It was observed too by SEM technique. Calix[4]arenequinhydrone is observed on the electrode surface as hexangular prisms with a length of few micrometers.

Section: Introductionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 98%

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Self-assembled calix[4]arenequinhydrone on the platinum electrode by cathodic reduction of calix[4]arenediquinone

Youchret-Zallez¹,

Besbes-Hentati²,

J Incl Phenom Macrocycl Chem

et al. 2011

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“…By analogy with the situation encountered with a calix [4]arenequinone [20], we finally concluded that neither the co-grinding nor the solvent-free approach would provide any ubiquinhydrone formation in the case of 1 and 2. This also holds for the 2,6-dimethoxy-1,4-quinone and its hydroquinone from which we have been unable to generate a quinhydrone derivative.…”

mentioning

confidence: 92%

A Ubiquinol‐Based Charge‐Transfer Complex Obtained from a Solvent‐Free Approach

Malézieux

Herson

et al. 2009

Helvetica Chimica Acta

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Quinones (¼ cyclohexa-2,5-diene-1,4-diones) and hydroquinones (¼ benzene-1,4-diols) belong to species that are balanced between their redox character and their ability to build supramolecular complexes. Considering the ubiquinol 2,3-dimethoxy-5-methyl-1,4-dihydroquinone (¼ 2,3-dimethoxy-5-methylbenzene-1,4-diol; 1), the tendency to undergo an oxidation side reaction was overcome by combining this electron-donating species 1 with a nonreactive partner, benzene-1,2,4,5-tetracarbonitrile (TCNB; 3), to yield a 2 : 1 charge-transfer (CT) complex 4. This work illustrates how very convenient the solvent-free techniques are to access intermolecular species. X-Ray diffraction studies revealed that pure ubiquinol 1 (structure included) crystallizes in two enantiomeric conformations, while the triads 4 formed with TCNB (3) exist as meso forms assembled via H-bonds in zigzag-chains patterns.

“…The calix[4]arenequinhydrone charge-transfer complex exhibits an intense solvatochromic absorption band in the visible region [27]. The charge-transfer complexes have been studied in solvents of low dielectric constant as described by Peover [28, 29] and its band energy has been characterized by UV–Vis spectroscopy [4].…”

Section: Introductionmentioning

confidence: 99%

Electrochemical and spectral studies of auto-assembled arrays of calix[4]arenequinhydrone charge-transfer complex on indium–tin oxide (ITO) glass

Youchret-Zallez¹,

Besbes-Hentati²,

J Incl Phenom Macrocycl Chem

et al. 2013

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A sensing materiel based on calix[4]arene molecules is electrochemically deposited on ITO electrode coated. A brown film was electrodeposited at a potential Eimp = –1.00 V versus SCE in acetonitrile solvent, however in dichloromethane solvent, a bluish film auto-assembled on the ITO electrode coated at a potential Eimp = −0.65 V versus SCE. Both films are subsequently analyzed by cyclic voltammetry and UV–Vis spectroscopy. This investigation shows that in acetonitrile solvent, the charge-transfer complex, calix[4]arenequinhydrone was formed in electrolytic solution and it was not self-assembled on the ITO electrode. The related UV–Vis spectrum shows a single absorption band towards a wavelength about 350 nm. The optical behaviour of the blue film shows two absorption bands: the first one appears on the first absorption band of the acceptor at 305 nm and the second one in the visible range at 502 nm. The band situated in the visible range correspond to a well-defined charge-transfer band indicating the presence of the charge-transfer complex, the calix[4]arenequinhydrone.